Days to germination: 4 to 6 days
Days to harvest: 3 years
Light requirements: Full sun
Water requirements: Regular watering
Soil: Sandy soil, even generally poor soil
Container: Not suitable due to the size of the plant
Cashews are a tropical plant, so you will only be able to grow them in countries like their native Brazil. Various regions such as central Africa, Southeast Asia and some parts of Australia are all well-suited for cashews. Southern Florida may be able to grow cashews depending on the immediate climate. It’s a perennial (a tree, actually) so you can’t have winter temperatures that drop below 50F (10C).
Other than the necessary tropical climate, cashews are actually very easy plants to grow. Growing cashew trees will not only provide you with the “nuts”, but also the unusual sweet fruit that grows along with them. Called the cashew apple, the fruit is edible, though quite astringent to the taste. It makes excellent fruit juice.
Cashew apples are extremely high in vitamin C, even more so than oranges. Actually, there can be 5 times as much C in a cashew apple than an orange. Cashew nuts are quite high in calories, but also provide a good dose of copper, magnesium and phosphorus.
Starting from Seed
Cashew trees can be started by seed, or you can purchase seedlings. Some fruit tree nurseries may also have grafted saplings (cashew branches grafted to another tree’s root stock) which will usually start to produce fruit sooner.
To plant a cashew, you need the entire seed not just the nut kernel. They will germinate and sprout fairly quickly, so most people just plant them out where they want their tree. No need for transplanting from a pot.
Plant your seeds in early spring, at a depth of around 3 inches. If you are planting for more than one tree, keep them about 30 feet apart. Choose a sunny location with sandy or well-drained soil. The trees will grow up to 40 feet fall, so make sure you plant there where they will have room to grow. Cashew seeds germinate well, so you shouldn’t need to plant more than one seed in each location. If you prefer, plant 2 or 3 and then thin down to 1 should they all sprout.
Sandy soils are usually poor when it comes to nutrients, but cashews will do fine without too much additional fertilizer. You can give them a feeding once or twice a year with a standard fertilizer mixture if you wish. Water your trees whenever there is a dry spell, but you shouldn’t need to water them frequently otherwise.
Even once the tree is well-established, keep the area around it free of weeds.
Pests and Diseases
There aren’t really any devastating pests specific for the cashew tree, though you can always have trouble with all sorts of general leaf-eating insects. Twig borers and leaf miners are two that can cause you problems.
The twig borers will eat into the smaller branches of the tree, eventually causing them to drop off. Leaf miners are very small insects that will bore through the leaves, creating fine little tunnels through them. Neither will really threaten a mature plant unless in very large numbers. Younger trees can have a harder time of it, so you might need to spray them with an insecticide designed for fruit trees.
Besides insects, cashews can be infected by Anthracnose fungus. It likes a lot of moisture, and is likely to strike when you’ve had a very wet season as the new leaves and fruits are developing. Infected areas start to grow watery lesions, and they eventually turn rusty brown as they grow. It can be treated with fungicide, after you have removed as much of the infected material as you can.
Once the fruits start to grow, larger pests can become a problem. All kinds of rodents as well as bats love cashew fruit. Try to pick them as soon as they are ripe, and you may need to put a fence around the tree to keep out the larger animals.
Harvest and Storage
Cashews won’t start to produce fruit until they are around 3 years old, though some grafted trees can start fruiting after only a year.
Your cashew trees will bloom during the winter, and you should have your fruit and nuts a few months later. Cashew fruits look a little bit like pears, with the nut growing at the end like a big knob.
The fruits will start off yellow, and eventually turn a deeper red. That’s when they are ripe. The nut portion should be gray. Try to get them picked before they fall to the ground. They bruise very easily and are more likely to be attacked by pests when on the ground.
Since each fruit only produces a single cashew nut, you may not want to process or shell them just a few at a time. Break the cashew pod off the end of the fruit, and you can store it like this for up to 2 years in a cool place. That way you can save up your harvest until you have enough to warrant the work involved in shelling. And they are a bit of work. You can eat or juice the fruit right away. Enjoy the fruit because there is almost no opportunity to purchase cashew apples commercially. This may be your only chance to eat one.
Inside the nut portion of the cashes is the nut meat, but also an acidic resin that will burn your hands. This makes cashew shelling a very tricky business. The easiest method is to freeze the nuts solid, and then crack open the shell. The acid will be solid and you should be able to remove the nut kernel with little mess. Even so, you must wear heavy rubber gloves and long sleeves when you shell your nuts.
Other methods include roasting the nuts over an open fire until the shells crack and the resin drips out. The fumes from this method are just as bad as the liquid itself, so don’t try it indoors.
If the processing seems too complicated, you can enjoy your cashew trees just for the sweet fruit. Many home gardeners do.